No Response From CAB
NOTE:
After making any repairs, perform ANTI-LOCK BRAKE SYSTEM VERIFICATION TEST under VERIFICATION TESTS.
NOTE:
Anti-lock Brake System (ABS) Controller Anti-Lock Brake (CAB) module may also be referred to as CAB controller.
- Turn ignition off. Connect scan tool to Data Link Connector (DLC). DLC is located on bottom of instrument panel, to left of brake pedal. See Figure. Turn ignition on. Using scan tool, attempt to communicate with other modules. If scan tool does not communicate with other modules, proceed to NO RESPONSE FROM PCI (PCI BUS) test. If scan tool communicates with other modules, go to next step.
- Turn ignition off. Remove and inspect fuse No. 11 from fuse block. If fuse is okay, leave fuse removed and go to next step. If fuse is open, repair short to ground on Dark Blue/White wire and replace fuse.
- Ensure ignition is off. Disconnect 25-pin CAB module connector. See Figure and Fig 1 . Check, clean and repair connectors as necessary. Using ohmmeter, check resistance between ground and CAB module connector terminals No. 8 and 24, ground circuits (Black wires). If resistance is less than one ohm in both circuits, go to next step. If resistance is one ohm or more on either circuit, repair open Black wire(s).
- Ensure ignition is off. Install fuse No. 11. Turn ignition on. Using a voltmeter, check voltage between CAB module connector terminal No. 4, fused ignition switch output start/run circuit (Dark Blue/White wire) and ground. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open Dark Blue/White wire.
- Turn ignition off. Connect scan tool to Data Link Connector (DLC). DLC is located on bottom of instrument panel, to left of brake pedal. See Figure. Turn ignition on. Using scan tool, attempt to communicate with other modules. If scan tool does not communicate with other modules, proceed to NO RESPONSE FROM PCI (PCI BUS) test. If scan tool communicates with other modules, go to next step.
- Connect Scope Input Cable (CH7058) to channel one connector on scan tool. Connect Red and Black leads, and Cable-to-Probe Adapter (CH7062) to scope input cable. Go to next step.
- Using scan tool, select DRB STANDALONE, LAB SCOPE, LIVE, then 12-VOLT SQUARE WAVE. Press F2 for scope. Press F2 again and use down arrow to set voltage range to 20 volts. Press F2 again. Go to next step.
- Connect Black lead to ground. Connect Red lead to ORC connector terminal No. 21, PCI bus circuit (Violet/Yellow wire). Turn ignition on. Observe voltage display on scan tool lab scope. If voltage pulses from zero to about 7.5 volts, replace CAB module. See appropriate ANTI-LOCK article in BRAKES. If voltage remains at zero volts, repair open Violet/Yellow wire. Perform BODY VERIFICATION TEST .